Sharing the model in MVP Winforms App
- by Keith G
I'm working on building up an MVP application (C# Winforms). My initial version is at http://stackoverflow.com/questions/1422343/ ... Now I'm increasing the complexity. I've broken out the code to handle two separate text fields into two view/presenter pairs. It's a trivial example, but it's to work out the details of multiple presenters sharing the same model.
My questions are about the model:
I am basically using a property changed event raised by the model for notifying views that something has changed. Is that a good approach? What if it gets to the point where I have 100 or 1000 properties? Is it still practical at that point?
Is instantiating the model in each presenter with NoteModel _model = NoteModel.Instance the correct approach? Note that I do want to make sure all of the presenters are sharing the same data.
If there is a better approach, I'm open to suggestions ....
My code looks like this:
NoteModel.cs
public class NoteModel : INotifyPropertyChanged
{
private static NoteModel _instance = null;
public static NoteModel Instance
{
get { return _instance; }
}
static NoteModel()
{
_instance = new NoteModel();
}
private NoteModel()
{
Initialize();
}
public string Filename { get; set; }
public bool IsDirty { get; set; }
public readonly string DefaultName = "Untitled.txt";
string _sText;
public string TheText
{
get { return _sText; }
set
{
_sText = value;
PropertyHasChanged("TheText");
}
}
string _sMoreText;
public string MoreText
{
get { return _sMoreText; }
set
{
_sMoreText = value;
PropertyHasChanged("MoreText");
}
}
public void Initialize()
{
Filename = DefaultName;
TheText = String.Empty;
MoreText = String.Empty;
IsDirty = false;
}
private void PropertyHasChanged(string sPropName)
{
IsDirty = true;
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(sPropName));
}
}
public event PropertyChangedEventHandler PropertyChanged;
}
TextEditorPresenter.cs
public class TextEditorPresenter
{
ITextEditorView _view;
NoteModel _model = NoteModel.Instance;
public TextEditorPresenter(ITextEditorView view)//, NoteModel model)
{
//_model = model;
_view = view;
_model.PropertyChanged += new PropertyChangedEventHandler(model_PropertyChanged);
}
void model_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "TheText")
_view.TheText = _model.TheText;
}
public void TextModified()
{
_model.TheText = _view.TheText;
}
public void ClearView()
{
_view.TheText = String.Empty;
}
}
TextEditor2Presenter.cs is essentially the same except it operates on _model.MoreText instead of _model.TheText.
ITextEditorView.cs
public interface ITextEditorView
{
string TheText { get; set; }
}
ITextEditor2View.cs
public interface ITextEditor2View
{
string MoreText { get; set; }
}
